As another example, the Path of Exile community moved off onto their own community-run wiki domain, but the Fandom variant (which is woefully out of date) continues to be one of the top results when searching for a PoE wiki page.

In some regards that's inevitable, but it clearly shows what Fandom's priorities are.

Backfired on them, the whole OSRS community was intentionally searching for things in google and using the “official” wiki results to bury fandom, then the game devs themselves added a wiki button into the game.

I don’t care what their rationale was, it’s to claim you own intellectual property that other people wrote for you. If I write a story, and post an excerpt to someone else’s website that doesn’t immediately confer copyright or IP ownership of that to the website owner.

Even more so when the information that is your IP is copied word for word from another companies IP and iterated on by a third party to qualify for fair use.